750 NOTES ON NORTH AMERICAN SHELLS STEARNS!. 



])erfectly in every other respect and also agree with examples in the 

 U. S. National Museum (No. 1151481) iVom Tucson, Ariz., present(Hl by 

 the late Dr. Isaac Lea. The Lea specimens, of which there are several, 

 inelnde examj)les that exhibit the characteristics of Triodop.sis, as well 

 as others, in Miiich the ]»eristome is simi)le or not tri(lentat(; or dentic- 

 ulate, in this respect being like other species that have been placed 

 iu the above genus, and show npon what an infirm fonndation some of 

 these genera are based. 



It is quite evident that liowev«;r persistent the tridentate character 

 may be in certain forms, in others it is variable, and therefore of lit- 

 tle value; the latter may be regarded as the connecting links which 

 unite Triodopsis to Mesodon. 



Bland's description* rests npon '' two living and one dead specimen," 

 collected by Dr. G. M. Levette, near Santa Fe, N. Mex. Binney, ([not- 

 ing Bland, says; '• this species is ([uite distinct from anj' known North 

 American or other form. The number of whorls aud of teeth, their 

 form and color, with the color of i\w shell aud peristome, are its 

 peculiar features. The strije are by no meaus so well developed as 

 shown in the figures." 



Further on, he observes: " the species varies iu the num))er of teeth 

 on the peristome. vSome have oik^ basal tooth only, which in some 

 specimens is widely aud bluntly bifid." 



Attention is called to the geographical extension of the range of this 

 species and of Patida sfrigosn var. HcmpliiUi ; for this addition to our 

 knowledge we have to thank Dr. Fisher and the Biological Division 

 of the Department of Agriculture. 



From the habitat of Dr. Levette's examples to Tucson, the locality 

 of the Lea specimens, aud Fort Huacliuca, is nearly 400 miles iu a 

 southwesterly direction ; the latter place is so very near the boundary 

 line between the state of Sonora, Mexico, and the United States, that 

 there can be hardly a doubt that further exploration of the general 

 region will detect both H. {Patula) HemphiUi and H. (Triodopsis) 

 Lerettei south of the boundary, and add their names to the list of the 

 Mexican fauna. 



(ienns ARIONTA Leach. 



Sociion LYSrXOE U. ami A. Ailams. 



Helix (Ariouta) californiensis Lea. 



One specimen, dead. 



Monterey, Cal., "iu the woods," October 8, 1891; Vernon Bailey. 



A familiar form, which seems to have its specific center iu this region. 

 I collected a large number of the above at this x)lace iu ^March, 18G7, in 

 openings on grassy slojjes. 



Biniiey's Manual oi' Ain. Land Shells ( Hull. 28, U. S. Nat. Mas.), p. 385, 386, fig. 419. 



